MICROORGANISMS IN WATER. 



197 



Average annual death rate from typhoid fever per 100,000 of the population. 



8 16 24 32 40 48 56 64 72 80 88 96 104 112 120 DEATHS 



BERLIN 



ZURICH 



HAMBURG 



PARIS 



LONDON 



PATERSON 



BIHGHAMPTON 



ALBANY 



LAWRENCE 



WATERTQWN 



MINNEAPOLI 

 ATTLE 



NEW'ORLEANS 



TOLEDO 



PRIN6FIELD 

 WILMINGTON 

 RICHMOND 

 CINCINNATI 

 LOUISVILLE 

 PHILADELPHIA 

 ATLANTA 

 WHEELING 



ALLE6ANY 

 PITTSBURG 



An instructive contrast between Altdffa"hud Hamburg before the latter 

 filtered its water, having learnt its lesson from a sharp outbreak of cholera. 



A FEW 

 SCATTERED 



CASES Or 



POPULATION: 600.000 

 CHOLERA CASES: 17.000 

 .. DEATHS: 8,600 



ALTONA'- 



WATER FILTERED 



HAMBURG: 



"WATER UNFILTERED 



FIG. 57 .(After G. E. Armstrong.} 



